Solid AB has the NaCl structure. Atom A  occupy the corners of the cubic unit cell. If all the face centered atoms along one of the axes are removed, then the resultant stoichiometry of the solid is

Given solid AB has NaCl structure   A+≡Na+−Face centre + corners    B−−  Cl−− BodyCentre+Edge centers ⇒ A4B4  but Face centers along                   one axis i.e., 2×12=1  are  removed              ∴ formulae is A3B4